U.S. patent application number 12/695785 was filed with the patent office on 2010-07-29 for signal transmission scheme for efficient management of common enhanced dedicated channel.
Invention is credited to Sung Duck Chun, Sun Hee KIM, Sung Jun Park, Seung June Yi.
Application Number | 20100188969 12/695785 |
Document ID | / |
Family ID | 42370518 |
Filed Date | 2010-07-29 |
United States Patent
Application |
20100188969 |
Kind Code |
A1 |
KIM; Sun Hee ; et
al. |
July 29, 2010 |
SIGNAL TRANSMISSION SCHEME FOR EFFICIENT MANAGEMENT OF COMMON
ENHANCED DEDICATED CHANNEL
Abstract
A signal transmission scheme for efficient management of a
common E-DCH is provided. In the case of a common E-DCH that a UE
in an idle mode or in a CELL_FACH status uses within a limited
period of time, the UE may notify a Node B of release of radio
resources of the common E-DCH using scheduling information
including TEBS=0 within the period of time when the UE has
completed data transmission. It is possible to prevent unnecessary
waste of resources and unnecessary battery consumption of the UE by
taking into consideration the above circumstances when triggering
new scheduling information since HARQ transmission of the
scheduling information has failed.
Inventors: |
KIM; Sun Hee; (Anyang-Si,
KR) ; Yi; Seung June; (Anyang-Si, KR) ; Chun;
Sung Duck; (Anyang-Si, KR) ; Park; Sung Jun;
(Anyang-Si, KR) |
Correspondence
Address: |
BIRCH STEWART KOLASCH & BIRCH
PO BOX 747
FALLS CHURCH
VA
22040-0747
US
|
Family ID: |
42370518 |
Appl. No.: |
12/695785 |
Filed: |
January 28, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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61148370 |
Jan 29, 2009 |
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61149007 |
Feb 1, 2009 |
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61149313 |
Feb 2, 2009 |
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61151196 |
Feb 10, 2009 |
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61151510 |
Feb 11, 2009 |
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Current U.S.
Class: |
370/216 |
Current CPC
Class: |
Y02D 30/70 20200801;
Y02D 70/124 20180101; H04L 1/1887 20130101; H04L 1/1854 20130101;
H04W 72/1284 20130101 |
Class at
Publication: |
370/216 |
International
Class: |
G06F 11/00 20060101
G06F011/00 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 27, 2009 |
KR |
10-2009-0115861 |
Claims
1. A method for transmitting signals to a Node B by a User
Equipment (UE) using a Hybrid Automatic Repeat Request (HARQ)
scheme, the method comprising: transmitting a Medium Access Control
Protocol Data Unit (MAC PDU) including first scheduling information
and data to the Node B; determining whether or not a Total E-DCH
Buffer Status (TEBS) field of the first scheduling information is
set to 0 when the transmission of the MAC PDU has failed;
triggering second scheduling information as new scheduling
information when the TEBS field of the first scheduling information
is not set to 0; and transmitting the second scheduling information
to the Node B.
2. The method of claim 1, wherein the UE uses a common Enhanced
Dedicated Channel (E-DCH) within a limited period of time.
3. The method of claim 2, wherein resources for the common E-DCH
are shared with a plurality of UEs in an idle mode and a CELL_FACH
state.
4. The method of claim 3, further comprising: releasing the
resources for the common E-DCH when a HARQ buffer of a HARQ process
corresponding to the transmission of the MAC PDU is empty after the
transmission of the MAC PDU.
5. The method of claim 4, wherein transmitting the second
scheduling information comprises: performing random access to the
Node B; and generating a MAC PDU including the second scheduling
information and transmitting the MAC PDU including the second
scheduling information to the Node B.
6. The method of claim 2, wherein determining whether or not a
Total E-DCH Buffer Status (TEBS) field of the first scheduling
information is set to 0 comprises determining whether or not the UE
is in a CELL-FACH state or an idle mode, and wherein the second
scheduling information is triggered when the TEBS field of the
first scheduling information is not set to 0 or when the UE is
neither in a CELL-FACH state nor in an idle mode.
7. The method of claim 6, wherein the UE does not trigger the
second scheduling information when the TEBS field of the first
scheduling information is set to 0 and the UE is in a CELL_FACH
state or an idle mode.
8. A User Equipment (UE) for transmitting signals to a Node B using
a Hybrid Automatic Repeat Request (HARQ) scheme, the UE comprising:
a HARQ entity for managing one or more HARQ processes and
controlling HARQ transmission of signals to the Node B; and a
transmission module for transmitting a Medium Access Control
Protocol Data Unit (MAC PDU) including first scheduling information
and data to the Node B in association with a specific one of the
one or more HARQ processes, and wherein the HARQ entity determines
whether or not a Total E-DCH Buffer Status (TEBS) field of the
first scheduling information is set to 0 when the transmission of
the MAC PDU has failed and triggers second scheduling information
as new scheduling information when the TEBS field of the first
scheduling information is not set to 0, and transmits the second
scheduling information to the Node B through the transmission
module.
9. The UE of claim 8, wherein the UE is designed to use a common
Enhanced Dedicated Channel (E-DCH) within a limited period of
time.
10. The UE of claim 9, wherein resources for the common E-DCH are
shared with a plurality of UEs in an idle mode and a CELL_FACH
state.
11. The UE of claim 10, wherein the UE is designed to release the
resources for the common E-DCH if the specific HARQ process has
failed to transmit the MAC PDU when a HARQ buffer of a HARQ process
corresponding to transmission of the MAC PDU is empty after the MAC
PDU is transmitted.
12. The UE of claim 11, wherein the UE is designed to perform
random access to the Node B and to generate and transmit a MAC PDU
including the second scheduling information to the Node B in order
to transmit the second scheduling information to the Node B.
13. The UE of claim 9, wherein the HARQ entity is designed to
additionally determine, when determining whether or not a Total
E-DCH Buffer Status (TEBS) field of the first scheduling
information is set to 0, whether or not the UE is in a CELL-FACH
state or an idle mode, and to trigger the second scheduling
information when the TEBS field of the first scheduling information
is not set to 0 or when the UE is neither in a CELL-FACH state or
in an idle mode.
14. The UE of claim 13, wherein the HARQ entity is designed not to
trigger the second scheduling information when the TEBS field of
the first scheduling information is set to 0 and the UE is in a
CELL_FACH state or an idle mode.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Application Nos. 61/148,370, 61/149,007, 61/149,313, 61/151,196 and
61/151,510, filed on Jan. 29, 2009, Feb. 1, 2009, Feb. 2, 2009,
Feb. 10, 2009 and Feb. 11, 2009, respectively, which are hereby
incorporated by reference as if fully set forth herein.
[0002] This application claims the benefit of Korean Patent
Application No. 10-2009-0115861, filed on Nov. 27, 2009, which is
hereby incorporated by reference as if fully set forth herein.
BACKGROUND OF THE INVENTION
[0003] 1. Field of the Invention
[0004] The following description relates to a mobile communication
system, and more particularly, to a method for setting a scheduling
information triggering condition for efficiently managing a common
Enhanced Dedicated Channel (E-DCH).
[0005] 2. Discussion of the Related Art
[0006] First, a Universal Mobile Telecommunications System (UMTS)
to which the present invention is applied is described as
follows.
[0007] FIG. 1 illustrates a network structure of the UMTS.
[0008] The UMTS system mainly includes a User Equipment (UE), a
UMTS Terrestrial Radio Access Network (UTRAN), and a Core Network
(CN). The UTRAN includes one or more Radio Network Sub-systems
(RNSs) and each RNS includes a Radio Network Controller (RNC) and
one or more base stations (Node Bs) managed by the RNC. One Node B
has one or more cells.
[0009] FIG. 2 illustrates a wireless (or radio) protocol structure
used in the UMTS.
[0010] Pairs of wireless protocols, which are present in the UE and
the UTRAN, are responsible for transmitting data in wireless
intervals. Each wireless protocol layer will now be described.
First, a physical (PHY) layer, which is the first layer, functions
to transmit data in a wireless interval using various wireless
transmission technologies. The PHY layer is responsible for
reliable data transmission in wireless intervals. The PHY layer is
connected to a MAC layer, which is a higher layer, through a
transport channel. The transport channel is classified into a
dedicated transport channel and a common transport channel
according to whether the channel is shared or not.
[0011] The second layer includes Medium Access Control (MAC), Radio
Link Control (RLC), Packet Data Convergence Protocol (PDCP), and
Broadcast/Multicast Control (BMC) layers. The MAC layer is
responsible for mapping various logical channels to various
transport channels and is also responsible for logical channel
multiplexing to map various logical channels to a single transport
channel. The MAC layer is connected to the RLC layer, which is a
higher layer, through a logical channel. The logical channel is
mainly classified into a control channel used to transmit control
plane information and a traffic channel used to transmit user plane
information, according to the type of transmitted information.
[0012] The MAC layer is further classified into a MAC-b sublayer, a
MAC-d sublayer, a MAC-c/sh sublayer, a MAC-hs/ehs sublayer, and a
MAC-e/es or MAC-i/is sublayer, according to the type of managed
transport channel. The MAC-b sublayer is responsible for managing a
broadcast channel (BCH) which is a transport channel responsible
for broadcasting system information. The MAC-c/sh sublayer is
responsible for managing a common transport channel such as a
forward access channel (FACH) which is shared with other UEs. The
MAC-d sublayer is responsible for managing a dedicated channel
(DCH) or an enhanced dedicated channel (E-DCH) which is a transport
channel dedicated to a specific UE. In order to support high-speed
uplink and downlink data transmission, the MAC-hs/ehs sublayer
manages a high-speed downlink shared channel (HS-DSCH) which is a
transport channel for high-speed downlink data transmission and the
MAC-e/es or MAC-i/is sublayer manages an enhanced dedicated channel
(E-DCH) which is a transport channel for high-speed uplink data
transmission.
[0013] The RLC layer is responsible for guaranteeing a QoS of each
radio bearer (RB) and transmitting data according to the QoS. The
RLC has one or two independent RLC entities for each RB in order to
guarantee the inherent QoS of the RB and provides three modes, a
transparent mode (TM), an unacknowledged mode (UM), and an
acknowledged mode (AM), in order to support various QoSs. The RLC
serves to adjust the size of data so as to be suitable for a lower
layer to transmit the data in a wireless interval. To accomplish
this, the RLC also functions to split and connect data received
from a higher layer.
[0014] The PDCP layer, which is located above the RLC layer, allows
data to be efficiently transmitted in a wireless interval with a
relatively small bandwidth using an IP packet such as IPv4 or IPv6.
To accomplish this, the PDCP layer performs a header compression
function which allows only indispensable information to be
transmitted in a data header, thereby increasing the efficiency of
transmission in wireless intervals. The PDCP layer is present
mainly in the PS domain since the header compression is a basic
function. One PDCP entity is present for each RB in order to
provide an efficient header compression function for each PS
service. The PDCP layer does not provide the header compression
function when it is present in the CS domain.
[0015] The second layer also includes a broadcast/multicast control
(BMC) layer above the RLC layer. The BMC layer functions to
schedule cell broadcast messages and to perform broadcasting to UEs
located in a specific cell.
[0016] The Radio Resource Control (RRC) layer, which is located at
the bottom of the third layer, is defined only in the control
plane. The RRC layer is responsible for controlling first and
second layer parameters in association with setup, reset, and
release of RBs and for controlling logical, transport, and physical
channels. The RB is a logical path that the first and second layers
of the wireless protocol provide for data transfer between the UE
and the UTRAN. Setup of an RB is generally a process for defining
characteristics of wireless protocol layers and channels required
to provide a specific service and for setting their respective
specific parameters and operating methods.
[0017] The following is a more detailed description of the
E-DCH.
[0018] The E-DCH is a transport channel dedicated to a single UE
which is used to transmit uplink data to a Node B in the UTRAN. In
order to transmit data at a high rate, the E-DCH uses technologies
such as Hybrid ARQ (HARQ), Adaptive Modulation and Coding (AMC),
and Node B controlled scheduling.
[0019] For the E-DCH, the Node B transmits downlink control
information, which controls E-DCH transmission of the UE, to the
UE. The downlink control information includes acknowledgement
information (ACK/NACK) for HARQ, channel quality information for
AMC, and E-DCH transmission power allocation information for Node B
controlled scheduling, or the like.
[0020] On the other hand, the UE transmits uplink control
information to the Node B. The uplink control information includes
E-DCH UE buffer status information for Node B controlled
scheduling, UE power status information, the size of payload
indicated by an E-TFCI, retransmission count, UE power surplus
status report, or the like.
[0021] E-DCH transmission of the UE is controlled by the Node B.
The E-DCH control of the Node B is performed by a scheduler which
is responsible for allocating optimal radio resources to each UE.
Specifically, the scheduler allocates a large amount of radio
resources to a UE that is in a good radio channel condition and
allocates a small amount of radio resources to a UE that is in a
bad radio channel condition so as to reduce interference in the
uplink radio channel.
[0022] The scheduler allocates radio resources taking into
consideration not only the radio channel condition of the UE but
also information such as the amount of available power that the UE
can use for the E-DCH or the amount of data that the UE desires to
transmit. That is, the scheduler allocates optimal radio resources
to a UE, which has remaining power for the E-DCH and also has data
for transmission in uplink, taking into consideration the radio
channel condition.
[0023] Accordingly, to transmit data through the E-DCH, first, the
UE notifies the Node B of the amount of power available to the UE
and the amount of data for transmission. The amount of available
power and the amount of data for transmission of the UE are
transmitted through Scheduling Information (SI), a detailed
structure of which is illustrated in FIG. 3.
[0024] FIG. 3 illustrates a structure of the scheduling
information.
[0025] The following is a description of parameters included in the
scheduling information as shown in FIG. 3.
[0026] UE Power Headroom (UPH) indicates the ratio of the amount of
power that the UE currently uses to the maximum amount of power
available to the UE and thus indicates the amount of available
power that the UE can use for the E-DCH.
[0027] Total E-DCH Buffer Status (TEBS) indicates, in bytes, the
total amount of data of the UE awaiting transmission in the RLC and
MAC layers. TEES indicates the total amount of data using an index
in the range of 0 to 31 as illustrated in the following Table
1.
TABLE-US-00001 TABLE 1 Index TEBS value (bytes) 0 TEBS = 0 1 0 <
TEBS = 10 2 10 < TEBS = 14 3 14 < TEBS = 18 4 18 < TEBS =
24 . . . . . . 30 28339 < TEBS = 37642 31 37642 < TEBS
[0028] For example, the TEBS is set to 0 (TEBS=0) if the total
amount of data of the UE awaiting transmission is 0 byte and is set
to 29 (TEBS=29) if the total amount of data is 29 bytes.
[0029] Highest priority Logical channel Buffer Status (HLBS)
indicates the ratio of the amount of data of a highest priority
logical channel to the total amount of UE data for transmission.
Specifically, the HLBS indicates an index corresponding to
100.times.(the amount of highest priority logical channel data/the
total amount of UE data for transmission).
[0030] Highest priority Logical channel ID (HLID) indicates the
highest priority logical channel among logical channels having data
for transmission.
[0031] The UE should transmit the scheduling information only in a
specific condition for efficient use of radio resources instead of
transmitting the scheduling information each time. To accomplish
this, 3GPP currently defines the following conditions for
triggering generation of scheduling information.
TABLE-US-00002 TABLE 2 Scheduling information Triggering Conditions
when new data for transmission is generated in UE. when data for
transmission is generated in logical channel with higher priority
than logical channel in which data awaiting transmission is
present. when HARQ transmission of MAC PDU including data and
scheduling information has failed. when a predetermined time is
reached at regular intervals.
[0032] When scheduling information is generated when one of the
triggering conditions is satisfied, the UE transmits a Medium
Access Control Packet Data Unit (MAC PDU) including the scheduling
information to the Node B. The MAC PDU generally includes
higher-layer data and scheduling information. The MAC PDU may
include scheduling information alone when higher-layer data is
absent. The generated MAC PDU is transmitted to the Node B through
a HARQ process in the MAC layer.
[0033] If the UE notifies the Node B of UE power and data status
through scheduling information, the scheduler of the Node B
determines the amount of power available to the UE for E-DCH
transmission taking into consideration the status of the UE and the
entire radio status of the cell and notifies the UE of the
determined amount of available power through a downlink control
signal. The downlink control signal notifying the UE of the amount
of power is classified into two types, an Absolute Grant (AG)
indicating an absolute value of the amount of power available to
the UE and a Relative Grant (RG) indicating a value of the amount
of power available to the UE relative to the amount of previously
used power. Upon receiving the AG or RG downlink control signal,
the UE determines the amount of power for use in E-DCH transmission
and determines the size of a MAC PDU for transmission according to
the determined amount of power.
[0034] On the other hand, the 3GPP standard defines a common
Enhanced Dedicated Channel (common E-DCH) to allow a number of UEs
to commonly use the E-DCH under control of the Node B.
SUMMARY OF THE INVENTION
[0035] There is a need to increase the efficiency of processes of
the UE and to efficiently reduce unnecessary waste of resources
when transmitting scheduling information for the common E-DCH.
[0036] Accordingly, the present invention is directed to a signal
transmission scheme for efficient management of a common E-DCH that
substantially obviates one or more problems due to limitations and
disadvantages of the related art.
[0037] Additional advantages, objects, and features of the
invention will be set forth in part in the description which
follows and in part will become apparent to those having ordinary
skill in the art upon examination of the following or may be
learned from practice of the invention. The objectives and other
advantages of the invention may be realized and attained by the
structure particularly pointed out in the written description and
claims hereof as well as the appended drawings.
[0038] To achieve these objects and other advantages and in
accordance with the purpose of the invention, as embodied and
broadly described herein, a method for transmitting signals to a
Node B by a User Equipment (UE) using a Hybrid Automatic Repeat
Request (HARQ) scheme includes transmitting a Medium Access Control
Protocol Data Unit (MAC PDU) including first scheduling information
and data to the Node B, determining whether or not a Total E-DCH
Buffer Status (TEBS) field of the first scheduling information is
set to 0 when the transmission of the MAC PDU has failed,
triggering second scheduling information as new scheduling
information when the TEBS field of the first scheduling information
is not set to 0, and transmitting the second scheduling information
to the Node B.
[0039] Here, the UE may use a common Enhanced Dedicated Channel
(E-DCH) within a limited period of time and resources for the
common E-DCH may be shared with a plurality of UEs in an idle mode
and a CELL_FACH state.
[0040] The method may further include releasing the resources for
the common E-DCH when the transmission of the MAC PDU has failed
and the step of transmitting the second scheduling information may
includes performing random access to the Node B, and generating a
MAC PDU including the second scheduling information and
transmitting the MAC PDU including the second scheduling
information to the Node B.
[0041] In addition, the step of determining whether or not a Total
E-DCH Buffer Status (TEBS) field of the first scheduling
information is set to 0 may include determining whether or not the
UE is in a CELL-FACH state or an idle mode, and the second
scheduling information may be triggered when the TEBS field of the
first scheduling information is not set to 0 or when the UE is
neither in a CELL-FACH state nor in an idle mode.
[0042] Further, the second scheduling information may not be
triggered when the transmission of the MAC PDU has failed and the
TEBS field of the first scheduling information has been set to 0
and the UE is in a CELL_FACH state or an idle mode.
[0043] In another aspect of the present invention, a User Equipment
(UE) for transmitting signals to a Node B using a Hybrid Automatic
Repeat Request (HARQ) scheme includes a HARQ entity for managing
one or more HARQ processes and controlling HARQ transmission of
signals to the Node B, and a transmission module for transmitting a
Medium Access Control Protocol Data Unit (MAC PDU) including first
scheduling information and data to the Node B in association with a
specific one of the one or more HARQ processes, wherein the HARQ
entity determines whether or not a Total E-DCH Buffer Status (TEBS)
field of the first scheduling information is set to 0 when the
transmission of the MAC PDU has failed and triggers second
scheduling information as new scheduling information when the TEBS
field of the first scheduling information is not set to 0, and
transmits the second scheduling information to the Node B through
the transmission module.
[0044] In this embodiment, the UE is preferably designed to use a
common Enhanced Dedicated Channel (E-DCH) within a limited period
of time and resources for the common E-DCH may be shared with a
plurality of UEs in an idle mode and a CELL_FACH state.
[0045] The UE may be designed to release the resources for the
common E-DCH if the specific HARQ process has failed to transmit
the MAC PDU and the UE may be designed to perform random access to
the Node B and to generate and transmit a MAC PDU including the
second scheduling information to the Node B in order to transmit
the second scheduling information to the Node B.
[0046] In addition, the HARQ entity may be designed to additionally
determine, when determining whether or not a Total E-DCH Buffer
Status (TEBS) field of the first scheduling information is set to
0, whether or not the UE is in a CELL-FACH state or an idle mode,
and to trigger the second scheduling information when the TEES
field of the first scheduling information is not set to 0 or when
the UE is neither in a CELL-FACH state or in an idle mode.
[0047] Further, the HARQ entity may be designed not to trigger the
second scheduling information when the specific HARQ process has
failed to transmit the MAC PDU and the TEBS field of the first
scheduling information has been set to 0 and the UE is in a
CELL_FACH state or an idle mode.
[0048] According to embodiments of the present invention, the UE
does not transmit new scheduling information requesting release of
radio resources, which have already been released, when HARQ
transmission has failed, thereby avoiding unnecessary transmission
of scheduling information of the UE and unnecessary resource
allocation of the network.
[0049] It is to be understood that both the foregoing general
description and the following detailed description of the present
invention are exemplary and explanatory and are intended to provide
further explanation of the invention as claimed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0050] The accompanying drawings, which are included to provide a
further understanding of the invention and are incorporated in and
constitute a part of this application, illustrate embodiment(s) of
the invention and together with the description serve to explain
the principle of the invention. In the drawings:
[0051] FIG. 1 illustrates a network structure of the UMTS;
[0052] FIG. 2 illustrates a wireless (or radio) protocol structure
used in the UMTS;
[0053] FIG. 3 illustrates a structure of scheduling
information;
[0054] FIG. 4 illustrates a procedure for releasing common E-DCH
radio resources through scheduling information of TEBS=0;
[0055] FIG. 5 illustrates a problem associated with a condition for
triggering scheduling information associated with a common
E-DCH;
[0056] FIG. 6 illustrates a method for triggering scheduling
information according to a preferred embodiment of the present
invention;
[0057] FIGS. 7A and 7B illustrate operations of a UE in an idle
mode or in a CELL_FACH status that uses a common E-DCH according to
an embodiment of the present invention;
[0058] FIGS. 8A and 8B illustrate a method for operating a UE that
uses a common E-DCH according to an embodiment of the present
invention; and
[0059] FIG. 9 illustrates a configuration of a processor of a UE
according to an embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0060] Reference will now be made in detail to the preferred
embodiments of the present invention with reference to the
accompanying drawings. The detailed description, which will be
given below with reference to the accompanying drawings, is
intended to explain exemplary embodiments of the present invention,
rather than to show the only embodiments that can be implemented
according to the invention. The following detailed description
includes specific details in order to provide a thorough
understanding of the present invention. However, it will be
apparent to those skilled in the art that the present invention may
be practiced without such specific details. For example, although
the following descriptions will be given in detail with reference
to the case where the mobile communication system is a 3GPP system,
the following descriptions, except those specific to 3GPP, may be
applied to any other mobile communication system.
[0061] In some instances, known structures and devices are omitted
or are shown in block diagram form, focusing on important features
of the structures and devices, so as not to obscure the concept of
the present invention. The same reference numbers will be used
throughout this specification to refer to the same or like
parts.
[0062] In the following description, the term "terminal" is used to
describe any mobile or stationary user device such as a User
Equipment (UE) or a Mobile Station (MS). In addition, the term
"base station" is used to describe any network node that
communicates with the terminal such as a Node B or an eNode B.
[0063] The following is a description of a common E-DCH to which
the present invention is applied.
[0064] An E-DCH is classified into a dedicated E-DCH that is
occupied by a specific UE and a common E-DCH that is shared by a
number of terminals (UEs). While the dedicated E-DCH is a transport
channel that is allocated only to a specific UE, the common E-DCH
is commonly allocated to a number of UEs under control of a base
station (Node B).
[0065] Radio resources of the common E-DCH are used only by UEs
that are in an idle mode or in a CELL_FACH status. The idle mode is
a state in which the UE is not connected to the network and the
CELL_FACH status is a state in which no dedicated channel is
allocated to the UE since the amount of data to be transmitted is
small although the UE is connected to the network. A common E-DCH
has been developed to enable UEs in the two states to perform
high-speed data transmission since no dedicated channels have been
allocated to UEs in the two states. Each UE should perform a random
access procedure when requesting allocation of radio resources of a
common E-DCH since multiple UEs may simultaneously attempt to use
the common E-DCH. An embodiment of the present invention suggests
that the Node B provide time information to a UE when allocating
common E-DCH radio resources to the UE to allow the UE to use the
radio resources only within a predetermined period of time.
[0066] When common E-DCH radio resources are allocated to a UE
according to this embodiment, the UE uses the common E-DCH radio
resources only within a predetermined period of time and releases,
when the predetermined period of time has expired, the common E-DCH
radio resources to allow another UE to use the released common
E-DCH radio resources. However, if the UE completes data
transmission before the predetermined period of time expires, the
UE may notify the Node B of the release of the common E-DCH radio
resources. Scheduling information of TEBS=0 is transmitted to
notify the Node B of the release of the common E-DCH radio
resources. When receiving the scheduling information of TEBS=0, the
Node B may release the common E-DCH radio resources of the UE
before the predetermined period of time expires since TEBS=0
indicates that the UE has no data for transmission.
[0067] FIG. 4 illustrates a procedure for releasing common E-DCH
radio resources through scheduling information of TEBS=0.
[0068] When a UE releases radio resources before a predetermined
period of time expires, the UE may generate scheduling information
of TEBS=0 (S401). Specifically, TEBS indicates data for
transmission/retransmission in an RLC buffer or remaining data in a
MAC buffer. Accordingly, when SI of TEBS=0 is triggered, a MAC PDU
transmitted with the SI of TEBS=0 includes the last data present in
the buffer. Thus, if the MAC PDU is transmitted, then all buffers
of the UE are empty.
[0069] Accordingly, the UE may transmit a MAC PDU including the
last data present in the UE buffer for transmission together with
the scheduling information generated as described above to the Node
B (S402). Transmission of the MAC PDU is performed through a
specific HARQ that is managed by a HARQ entity. The UE releases the
common E-DCH radio resources after waiting until HARQ transmission
of the generated MAC PDU is completed such that it is flushed
(i.e., removed) from the HARQ buffer.
[0070] For example, the MAC PDU transmitted as described above may
be received by the Node B (S403). Upon receiving the MAC PDU
including the scheduling information of TEBS=0 from the UE, the
Node B may release the common E-DCH radio resources in response to
the reception (S404). Thereafter, the Node B may transmit a
positive acknowledgement (ACK) to the MAC PDU received from the UE
(S405).
[0071] Upon receiving the ACK from the Node B (S406), the UE may
flush data of the HARQ buffer corresponding to the HARQ process
that is used for transmission of the MAC PDU at step S402 in
response to the ACK reception and may then release the common E-DCH
radio resources accordingly (S407).
[0072] The UE may flush the MAC PDU from the HARQ buffer in two
cases. The UE flushes the MAC PDU from the Node B when an ACK has
been received from the Node B since transmission of the MAC PDU is
successful as shown in FIG. 4. On the other hand, the UE may
determine that HARQ transmission of the MAC PDU has failed and
flush the MAC PDU from the HARQ buffer if transmission of the MAC
PDU is unsuccessful (i.e., no ACK is received from the Node B)
although the UE has transmitted the MAC PDU the maximum number of
times of retransmission.
[0073] If HARQ transmission has failed after the UE transmitted a
MAC PDU including the last data present in the UE buffer and
scheduling information of TEBS=0 in order to release common E-DCH
radio resources, the UE may release the common E-DCH radio
resources when the MAC PDU is flushed from the HARQ buffer,
regardless of whether or not transmission of the MAC PDU is
successful. In this case, the UE releases the common E-DCH radio
resources without further transmission in order to reduce waste of
radio resources since the Node B may have actually received the MAC
PDU (when an ACK has been lost) or may not have received the MAC
PDU (when transmission of the MAC PDU has failed).
[0074] However, the UE needs to trigger new scheduling information
when the UE has failed to perform HARQ transmission of a MAC PDU
including data and scheduling information, according to the
triggering condition of current scheduling information described
above with reference to Table 2. The same is true when the MAC PDU
includes information of TEBS=0 indicating release of common E-DCH
radio resources. In this case, the UE needs to trigger new
scheduling information although the UE does not have any further
data for transmission. This procedure is described below in detail
with reference to FIG. 5.
[0075] FIG. 5 illustrates a problem associated with a condition for
triggering scheduling information associated with a common
E-DCH.
[0076] When a UE, which is in a CELL_FACH status or in an idle mode
in which the UE uses a common E-DCH within a limited period of
time, has no data in an RLC transmission or retransmission buffer
or has no data in a MAC transmission buffer, the UE may trigger
scheduling information of TEBS=0 in order to notify a Node B of
release of radio resources of the common E-DCH (S501). Accordingly,
the UE may transmit a MAC PDU including higher layer data and
scheduling information of TEBS=0 to the Node B (S502). Upon
receiving the MAC PDU transmitted by the UE (S503), the Node B may
release the common E-DCH radio resources in response to the
reception (S504). The Node B may transmit an ACK to the UE in order
to notify the UE of successful reception of the MAC PDU (S505).
[0077] On the other hand, the UE may fail to receive the ACK
transmitted by the Node B as shown in FIG. 5. When the UE has
failed to receive the ACK, the UE may retransmit the MAC PDU until
the maximum HARQ transmission count is reached (S506 and S507).
However, the UE determines that the HARQ transmission has failed
and clears the HARQ buffer (S509) when the maximum HARQ triggering
count of the UE is reached because the MAC PDU transmitted by the
UE is not received by the Node B as illustrated at step S506 in
FIG. 5 or because a corresponding ACK transmitted by the Node B
(S508) is not received by the UE although the MAC PDU has been
successfully received by the Node B as illustrated at step S507.
When HARQ transmission has failed in this manner, the UE also
releases the common E-DCH radio resources as described above
(S510). In this case, the UE should trigger new scheduling
information even though the UE has no data for transmission since
HARQ transmission of data and scheduling information has failed
according to the current scheduling information triggering
condition described above with reference to Table 2 (S520). In
addition, the UE should perform a new random access procedure for
transmission of new scheduling information since the common E-DCH
radio resources have already been released. However, this causes
unnecessary battery consumption of the UE and unnecessary
allocation of common E-DCH radio resources of the Node B.
[0078] In summary, the scheduling information triggering condition
described in Table 2 has a problem in that the UE not only releases
common E-DCH radio resource but also triggers new scheduling
information when the UE has failed to perform HARQ transmission of
a MAC PDU including TEBS=0 indicating release of the common E-DCH
radio resources. In this case, in order to transmit TEBS=0 alone,
the UE should perform a new random access procedure to acquire
common E-DCH radio resources since the common E-DCH radio resources
have already been released.
[0079] Accordingly, a preferred embodiment of the present invention
suggests that, when a UE has failed to perform HARQ transmission of
scheduling information, the UE not immediately trigger new
scheduling information but additionally determine whether or not
TEBS of the scheduling information, HARQ transmission of which has
failed, is set to "0", thereby solving the above problem.
[0080] Specifically, this embodiment suggests that the UE trigger
new scheduling information and transmit the same to the Node B only
when TEBS of the scheduling information, HARQ transmission of which
has failed, is not to set "0".
[0081] FIG. 6 illustrates a method for triggering scheduling
information according to a preferred embodiment of the present
invention.
[0082] First, when a UE has transmitted scheduling information to a
Node B according to a HARQ scheme, the UE may fail to transmit a
MAC PDU due to failure of the Node B to receive the MAC PDU or
failure of the UE to receive an ACK transmitted by the Node B
(S601). This embodiment suggests that, when such a scheduling
information transmission failure has occurred, the UE not
immediately trigger new scheduling information but additionally
check a TEBS field of the scheduling information that has failed to
be transmitted to determine whether or not the TEBS of the
scheduling information is set to "0" (S602). When the TEBS of the
scheduling information that has failed to be transmitted is set to
"0" (i.e., TEBS=0), the UE no longer triggers scheduling
information (S605). That is, the UE according to this embodiment
may trigger new scheduling information only when the TEBS of the
scheduling information that has failed to be transmitted is not set
to "0".
[0083] Specifically, when the TEBS of the scheduling information
that has failed to be transmitted is not set to "0", the UE may
determine whether or not the scheduling information has been
transmitted together with data through a MAC PDU (S603). When it is
determined that the scheduling information has been transmitted
without data through a MAC PDU (i.e., a stand alone type MAC PDU),
the UE may no longer trigger scheduling information (S605). When
transmission of a MAC PDU including the scheduling information
alone (i.e., without data) has failed in this manner, the UE can
transmit scheduling information required for the next scheduling
information transmission period based on period scheduling.
[0084] On the other hand, when it is determined at step S603 that
the scheduling information, HARQ transmission of which has failed,
has been transmitted together with data through a MAC PDU, the UE
triggers new scheduling information (S604). Accordingly, the UE can
transmit both the newly triggered scheduling information and the
data through the MAC PDU to the Node B.
[0085] The following is a description of the case where a common
E-DCH is used using the scheduling information triggering condition
suggested as described above in comparison with the case where a
common E-DCH is used according to the conventional scheduling
scheme.
[0086] FIGS. 7A and 7B illustrate operations of a UE in an idle
mode or in a CELL_FACH status that uses a common E-DCH according to
an embodiment of the present invention.
[0087] FIG. 7A illustrates the case of using a general scheduling
information triggering condition and FIG. 7B illustrates the case
of using the scheduling information triggering condition according
to the embodiment described above with reference to FIG. 6.
[0088] First, when a UE, which is in a CELL_FACH status or in an
idle mode in which the UE uses a common E-DCH within a limited
period of time, transmits last data, the UE may transmit a MAC PDU
including the last data and scheduling information of TEBS=0 to a
Node B. In FIG. 7, it is assumed that the UE has failed to transmit
the MAC PDU (S701). When the UE has transmitted scheduling
information of TEBS=0 in order to notify the Node B of release of
common E-DCH radio resources in this manner, the UE may also
release the common E-DCH radio resources as described above with
reference to FIGS. 4 and 5 (S702).
[0089] In the case where the general scheduling information
triggering scheme is employed as shown in FIG. 7A, the UE triggers
new scheduling information when HARQ transmission of scheduling
information together with data has failed and creates a MAC PDU for
transmitting the new scheduling information (S703). However, the UE
has no radio resources for transmitting the triggered scheduling
information since radio resources for common E-DCH transmission
have already been released. Accordingly, the UE transmits the
created MAC PDU (S705) after performing a procedure for random
access to the Node B (S704) and acquiring uplink radio resources
from the Node B. However, retransmission of the scheduling
information from the UE causes unnecessary battery consumption of
the UE and unnecessary allocation of common E-DCH radio resources
of the Node B since the purpose of retransmission of the scheduling
information is only to notify the Node B of release of common E-DCH
radio resources.
[0090] On the other hand, in the case where the embodiment of the
present invention is employed as shown in FIG. 7B, the UE
additionally determines whether or not TEBS of scheduling
information is set to "0" when HARQ transmission of the scheduling
information has failed at step S706. That is, this embodiment
suggests that the UE perform an operation for transmitting new
scheduling information according to the procedure of steps S703 to
S705 only when the TEBS of the scheduling information, HARQ
transmission of which has failed, is not "0" and not longer trigger
scheduling information when the TEBS of the scheduling information,
HARQ transmission of which has failed, is "0".
[0091] The purpose of determining whether or not the TEBS of the
scheduling information is 0 at step S706 in FIG. 7 is to overcome
the problem that may occur when the common E-DCH is used as shown
in FIG. 5. Since the common E-DCH is used only by UEs that are in
an idle mode or in a CELL_FACH status, the operation for
transmitting new scheduling information according to the procedure
of steps S703 to S705 may be performed when the UE is neither in an
idle mode nor in a CELL_FACH status.
[0092] To overcome the problem illustrated in FIG. 5, another
embodiment of the present invention suggests a method in which new
scheduling information is triggered in the same manner as in the
general scheme while the triggered scheduling information is not
transmitted when TEBS of scheduling information, HARQ transmission
of which has failed, is set to 0.
[0093] FIGS. 8A and 8B illustrate a method for operating a UE that
uses a common E-DCH according to an embodiment of the present
invention.
[0094] FIG. 8A illustrates a method for operating a UE that uses a
general scheduling information triggering condition and FIG. 8B
illustrates a method for operating a UE according to the
embodiment.
[0095] The operating method of FIG. 8A is similar to that of FIG.
7A. That is, when a UE, which is in a CELL_FACH status or in an
idle mode in which the UE uses a common E-DCH within a limited
period of time, has transmitted last data, the UE may transmit a
MAC PDU including the last data and scheduling information of
TEBS=0 to a Node B. In FIG. 8, it is assumed that the UE has failed
to transmit the MAC PDU (S801). When the UE has transmitted
scheduling information of TEBS=0 in order to notify the Node B of
release of common E-DCH radio resources in this manner, the UE may
also release the common E-DCH radio resources as described above
with reference to FIGS. 4 and 5 (S802).
[0096] In the case where the general scheduling information
triggering scheme is employed as shown in FIG. 8A, the UE triggers
new scheduling information when HARQ transmission of scheduling
information together with data has failed and creates a MAC PDU for
transmitting the new scheduling information (S803). However, the UE
has no radio resources for transmitting the triggered scheduling
information since radio resources for common E-DCH transmission
have already been released. Accordingly, the UE transmits the
created MAC PDU (S805) after performing a procedure for random
access to the Node B (S804) and acquiring uplink radio resources
from the Node B. However, retransmission of the scheduling
information from the UE causes unnecessary battery consumption of
the UE and unnecessary allocation of common E-DCH radio resources
of the Node B since the purpose of retransmission of the scheduling
information is only to notify the Node B of release of common E-DCH
radio resources.
[0097] On the other hand, in the case where this embodiment is
employed as shown in FIG. 8B, the UE triggers new scheduling
information according to a general scheduling information
triggering algorithm when HARQ transmission of scheduling
information has failed at step S803-1. However, instead of
unconditionally creating and transmitting a MAC PDU for
transmitting the triggered scheduling information to the Node B,
the UE checks a TEBS field of the scheduling information, HARQ
transmission of which has failed, to determine whether or not TEBS
of the scheduling information, HARQ transmission of which has
failed, is 0 (S806). This embodiment suggests that the UE not
transmit the triggered scheduling information when the TEBS of the
scheduling information, HARQ transmission of which has failed, is
0. On the other hand, when the TEBS of the scheduling information,
HARQ transmission of which has failed, is not 0, the UE may create
a MAC PDU for transmitting the scheduling information triggered at
step S803-1 (S803-2) and perform subsequent operations for
transmitting the created MAC PDU (S804 and S805).
[0098] The UE according to the embodiments described above can
avoid unnecessary waste of resources and unnecessary operations
when using the common E-DCH.
[0099] The following is a description of the configuration of a UE
according to the embodiments described above.
[0100] In a mobile communication system, a UE may include an input
unit, a display module, and the like in addition to a processor for
signal processing. Among configurations of these components of the
UE, process structures that are responsible for actual signal
processing are mainly described below.
[0101] FIG. 9 illustrates a configuration of a processor of a UE
according to an embodiment of the present invention.
[0102] The processor of the UE may have the protocol structure as
described above with reference to FIG. 2 and embodiments of the
present invention are mainly associated with a physical layer 910,
a MAC layer 920, and an RLC layer 930 among the layers of the
protocol structure.
[0103] The MAC layer module 920 according to an embodiment of the
present invention may include a HARQ entity 921, one or more HARQ
processes 922, HARQ buffers 923 corresponding respectively to the
HARQ processes 922, an E-TFC selection entity & SI reporting
entity 924 that determines a MAC PDU size and transmission power
when transmitting a new MAC PDU, and a multiplexing entity 925 that
multiplexes scheduling information with data of a transmission
buffer 931 of an RLC layer above the MAC layer which is transmitted
every MAC-d flow. The UE includes one HARQ entity 921 which manages
one or more HARQ processes 922 and manages HARQ signal transmission
of the UE.
[0104] The physical layer module 910 may be simplified such that it
includes a transmission module 911 and a reception module 912. The
transmission module 911 may be responsible for transmitting a MAC
PDU received from the MAC layer module to the Node B and the
reception module 912 may be responsible for receiving a HARQ
feedback signal from the Node B in response to the MAC PDU
transmission from the UE.
[0105] The HARQ entity 921 of the UE may transmit a MAC PDU
including data and scheduling information to the Node B, in
association with a specific one of the one or more HARQ processes
922, through the transmission module 911 of the physical layer
module 910. An embodiment of the present invention suggests that,
when the specific HARQ process has failed to transmit the MAC PDU,
the HARQ entity 921 of the UE (the E-TFC selection entity & SI
reporting entity 924 in a more specific embodiment) determine
whether or not a TEBS field of scheduling information, HARQ
transmission of which has failed, is set to 011 and trigger new
scheduling information only when the TEBS field is not set to "0"
and transmit the triggered scheduling information to the Node B
through the transmission module 911.
[0106] An embodiment of the present invention suggests that the
HARQ entity 921 be designed to additionally determine whether or
not the UE is in an idle mode or in a CELL_FACH status when
determining whether or not the TEBS field of the scheduling
information is set to "0" and the UE be designed to transmit the
new scheduling information triggered in response to failure of the
HARQ transmission of the scheduling information when the UE is
neither in an idle mode nor in a CELL_FACH status.
[0107] As is apparent from the above description, the embodiments
of the present invention avoid unnecessary transmission of
scheduling information of a UE and unnecessary resource allocation
of a network since the UE does not transmit new scheduling
information requesting release of radio resources, which have
already been released, when HARQ transmission has failed.
[0108] Although the signal transmission/reception technologies and
the UE structures for accomplishing the technologies have been
described above with reference to examples where they are applied
to the 3GPP system, they may also be applied to various other types
of mobile communication systems having similar procedures.
[0109] The detailed description of the preferred embodiments of the
present invention has been given to enable those skilled in the art
to implement and practice the invention. Although the invention has
been described with reference to the preferred embodiments, those
skilled in the art will appreciate that various modifications and
variations can be made in the present invention without departing
from the spirit or scope of the invention described in the appended
claims. Accordingly, the invention should not be limited to the
specific embodiments described herein, but should be accorded the
broadest scope consistent with the principles and novel features
disclosed herein.
* * * * *